package com.wy.common.utils;


import org.springframework.stereotype.Component;

import java.security.*;
import javax.crypto.*;

/**
 * @ClassName: DES
 * @Description:DES加解密算法
 * @author weny.yang
 * @date Mar 25, 2021
 */

@Component
public class DES {

  private static String strDefaultKey = "12345678";    //默认的密钥
  private Cipher encryptCipher = null;
  private Cipher decryptCipher = null;

  /**
   * 构造函数 DES.使用默认密钥
   * @throws Exception
   */
  public DES() throws Exception {
    this(strDefaultKey);
  }



  /**
   * 构造函数 DES.使用指定的密钥
   * @throws Exception
   */
  public DES(String strKey) throws Exception {
    Security.addProvider(new com.sun.crypto.provider.SunJCE());
    Key key = getKey(strKey.getBytes());
    encryptCipher = Cipher.getInstance("DES");
    encryptCipher.init(Cipher.ENCRYPT_MODE, key);
    decryptCipher = Cipher.getInstance("DES");
    decryptCipher.init(Cipher.DECRYPT_MODE, key);
  }


  /**
   * @Title: encrypt
   * @Description:加密字符串
   * @param strIn 需加密的字符串
   * @return 加密后的字符串
   * @author weny.yang
   * @date Mar 25, 2021
   */
  public  String encrypt(String strIn) throws Exception {
    return byteArr2HexStr(encrypt(strIn.getBytes()));
  }


  /**
   * 加密字节数组
   * @param arrB 需加密的字节数组
   * @return 加密后的字节数组
   * @author weny.yang
   * @date Mar 25, 2021
   * @throws Exception
   */
  public byte[] encrypt(byte[] arrB) throws Exception {
    return encryptCipher.doFinal(arrB);
  }



  /**
   * 解密字符串
   * @param strIn 需解密的字符串
   * @return 解密后的字符串
   * @author weny.yang
   * @date Mar 25, 2021
   * @throws Exception
   */
  public String decrypt(String strIn) throws Exception {
    return new String(decrypt(hexStr2ByteArr(strIn)));
  }


  /**
   * 解密字节数组
   * @param arrB 需解密的字节数组
   * @return 解密后的字节数组
   * @author weny.yang
   * @date Mar 25, 2021
   * @throws Exception
   */
  public byte[] decrypt(byte[] arrB) throws Exception {
    return decryptCipher.doFinal(arrB);
  }



  /**
   * 从指定字符串生成密钥，密钥所需的字节数组长度为8位
   * 不足8位时后面补0，超出8位只取前8位
   * @param arrBTmp 构成该字符串的字节数组
   * @return 生成的密钥
   * @author weny.yang
   * @date Mar 25, 2021
   * @throws Exception
   */
  private Key getKey(byte[] arrBTmp) throws Exception {
    byte[] arrB = new byte[8];
    for (int i = 0; i < arrBTmp.length && i < arrB.length; i++) {
      arrB[i] = arrBTmp[i];
    }
    Key key = new javax.crypto.spec.SecretKeySpec(arrB, "DES");
    return key;
  }



  /**
   * 将byte数组转换为表示16进制值的字符串，
   * 如：byte[]{8,18}转换为：0813，
   * 和public static byte[] hexStr2ByteArr(String strIn)
   * 互为可逆的转换过程
   * @param arrB 需要转换的byte数组
   * @return 转换后的字符串
   * @author weny.yang
   * @date Mar 25, 2021
   * @throws Exception
   */
  public static String byteArr2HexStr(byte[] arrB) throws Exception {
    int iLen = arrB.length;
    StringBuffer sb = new StringBuffer(iLen * 2);
    for (int i = 0; i < iLen; i++) {
      int intTmp = arrB[i];
      while (intTmp < 0) {
        intTmp = intTmp + 256;
      }
      if (intTmp < 16) {
        sb.append("0");
      }
      sb.append(Integer.toString(intTmp, 16));
    }
    return sb.toString();
  }



  /**
   * 将表示16进制值的字符串转换为byte数组，
   * 和public static String byteArr2HexStr(byte[] arrB)
   * 互为可逆的转换过程
   * @param strIn 需要转换的字符串
   * @return 转换后的byte数组
   * @author weny.yang
   * @date Mar 25, 2021
   * @throws Exception
   */
  public static byte[] hexStr2ByteArr(String strIn) throws Exception {
    byte[] arrB = strIn.getBytes();
    int iLen = arrB.length;
    byte[] arrOut = new byte[iLen / 2];
    for (int i = 0; i < iLen; i = i + 2) {
      String strTmp = new String(arrB, i, 2);
      arrOut[i / 2] = (byte) Integer.parseInt(strTmp, 16);
    }
    return arrOut;
  }
}
